In a pulse welding process where a welding wire is directed through the commonly used contact tip of a welding gun as the tip is subjected to a pulsed current signal, it is advantageous to tailor the background current and peak current to create a ball and to propel the ball at a specific time toward the workpiece. It has been found that the creation of the molten metal ball on the end of the advancing electrode depends on the spacing between the workpiece and the actual contact point of the wire with the contact tip. This distance between the contact point and the workpiece should remain coordinated with the profile of the pulse current. In this manner, the melting of the ball and the propelling of the ball are timed with the actual pulses of the electric current. Such coordination maintains the stability of the arc and assures the quality of the welding process. In other welding processes such as short arc or spray MIG welding, the coordination of the ball and propelling force with the waveform profile is not critical. In these processes, conventional tips are used satisfactorily with both iron and aluminum. In some instances, this standard short tip when not used for MIG welding included a ceramic block spring biased into the passageway to engage the wire and force the wire against the passage. Such spring biased ceramic block in a short tip was only for the purpose of ensuring contact. Thus, its expense was not justified and it was not accepted practice. The present invention relates to a contact tip specially designed for use in pulse welding aluminum wire. The aluminum wire passing through the passage of the tip engages the surface of the passage somewhere in the length. This uncertainty as to the contact point of the aluminum wire as it passes through the long contact tip reduces the stability of the arc and affects the quality of the pulsed welding with aluminum wire. In view of this background, there is a need for creating a contact tip specially designed for pulse welding with aluminum wire. A contact tip specially designed for aluminum pulse welding should also overcome the requirement for a special contact tip for each diameter and type of aluminum wire. In the past, this diameter of the passage in the contact tip had to be especially sized for each aluminum wire. Indeed, the passage was sized for the heat expansion of the specific aluminum wire. The diameter of the passage was about 0.010 inches larger than the diameter of the aluminum wire being welded. This required a special tip for each aluminum wire diameter. It has also been found that the contact tip and aluminum wire expand differently according to the process being performed and the alloy of the aluminum. Thus, the tip had to be specially designed not only for the diameter of the aluminum wire, but also for the expansion caused by heating associated to the welding process. When using aluminum wire, the welding tip had to be specially and accurately controlled as to the diameter of the passage for both pulse welding by aluminum wire and regular MIG welding by aluminum wire. Consequently, there is a need for a tip to be used in aluminum, especially for aluminum pulse welding which need not be accurately dimensioned and still present a specific, fixed contact point. This feature increases the arc stability. Prior contact tip disadvantages for the pulse welding process have been overcome by the present invention.